Protocol misinterpretation avoidance apparatus and method for a tire pressure monitoring system

ABSTRACT

A determination is made as to whether a frame to be transmitted according to a first protocol is susceptible to being incorrectly interpreted by a receiver in a vehicle as being transmitted according to a second protocol. When the frame is determined to be susceptible to an incorrect interpretation, an internal value of the frame is adjusted, and the adjustment is effective to prevent an incorrect interpretation of the frame being transmitted from the tire pressure monitor to the receiver. The adjusted frame can then be transmitted.

CROSS REFERENCES TO RELATED APPLICATIONS

“Tire Pressure Monitoring Apparatus and Method” having Ser. No.13/206,255;

“Protocol Arrangement in a Tire Pressure Monitoring System” having Ser.No. 13/206,314; and

“Apparatus and Method for Activating a Localization Process for a TirePressure Monitor” having Ser. No. 13/206,336

all of which being filed on the same date as the present application andall of which having their contents incorporated herein by reference intheir entireties.

FIELD OF THE INVENTION

The field of the invention relates to tire pressure monitoring devicesthat utilize potentially different transmission protocols.

BACKGROUND

The pressure and other operating parameters of tires are importantconcerns when operating a vehicle. Not only can incorrect tire pressure(or the incorrect setting of some other tire parameter) lead toinefficient vehicle operation (e.g., the waste of fuel and otherproblems leading to higher operating costs), but too low a tire pressure(or an inadequate value for some other tire parameter) can lead tosafety problems such as accidents. It is difficult and sometimestime-consuming for users to manually measure tire pressure (or otherparameters) with a pressure gauge (or other instruments). Consequently,automatic tire pressure monitoring systems have been devised and thesesystems free the user from manually making tire measurements.

An automatic tire pressure monitoring device typically mounts to a wheelwithin the tire and wirelessly transmits information indicative ofconditions within the tire. The transmissions and the order ofinformation are typically defined by a protocol corresponding to areceiver within the vehicle. Once the receiver receives the information,the information can be processed and presented to a user. For instance,a user can be warned when the pressure in their tires is too high or toolow and thus avoid safety problems. Each automobile manufacturertypically has a unique, preferred, and pre-defined protocol to meetapplication specific needs and applications. Consequently, receiversusing one manufacturers' protocol are generally not responsive totransmitters operating according to other manufacturers' protocols.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 comprises a block diagram of a tire pressure monitoring systemaccording to various embodiments of the present invention;

FIG. 2 comprises a flowchart showing one example of an approach formonitoring pressure and/or other parameters of a tire according tovarious embodiments of the present invention;

FIG. 3 comprises a block diagram of another example of a tire pressuremonitoring apparatus according to various embodiments of the presentinvention;

FIG. 4 comprises a block diagram of transmission burst formats accordingto various embodiments of the present invention;

FIG. 5 comprises a flowchart of one approach for preventing protocolmisinterpretation in a tire pressure monitoring system;

FIG. 6 comprises a block diagram and related flowchart of one approachfor preventing protocol misinterpretation in a tire pressure monitoringsystem.

Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions and/or relative positioningof some of the elements in the figures may be exaggerated relative toother elements to help to improve understanding of various embodimentsof the present invention. Also, common but well-understood elements thatare useful or necessary in a commercially feasible embodiment are oftennot depicted in order to facilitate a less obstructed view of thesevarious embodiments of the present invention. It will further beappreciated that certain actions and/or steps may be described ordepicted in a particular order of occurrence while those skilled in theart will understand that such specificity with respect to sequence isnot actually required. It will also be understood that the terms andexpressions used herein have the ordinary meaning as is accorded to suchterms and expressions with respect to their corresponding respectiveareas of inquiry and study except where specific meanings have otherwisebeen set forth herein.

DETAILED DESCRIPTION

Approaches are provided where a tire pressure monitor makes dynamicadjustments to transmitted frames on a frame-by-frame basis (as eachframe is transmitted) so that misinterpretation of these frames atreceivers is avoided or prevented. The approaches are implemented at thetire pressure monitor and are transparent to end-users. Since end-userinvolvement is eliminated, the approaches are easy to use and increasethe reliability and performance of the tire pressure monitoring system.

In many of these embodiments, a determination is made as to whether aframe to be transmitted according to a first protocol is susceptible tobeing incorrectly interpreted by a receiver in a vehicle as beingtransmitted according to a second protocol. When the frame is determinedto be susceptible to an incorrect interpretation, an internal value ofthe frame is adjusted, and the adjustment is effective to prevent anincorrect interpretation of the frame being transmitted from the tirepressure monitor to the receiver. The adjusted frame can then betransmitted from the tire pressure monitor. The internal adjustment actis selected so as to have the least impact on the meaning of the datatransmitted.

In some aspects, the adjusting flips at least one bit in the frame. Inother aspects, the determining calculates a checksum in the frameaccording to the checksum determination approach used by the secondprotocol. Still further, the checksum may be compared to a field in theframe that would be the checksum field according to the second protocol.When the calculated checksum equals the value of the field, a possiblemisinterpretation may occur. When the possible misinterpretation mayoccur, at least one bit is flipped in the frame.

In others of these embodiments, an apparatus for avoiding protocolmisinterpretation in a tire pressure monitoring system includes atransmission buffer, a transmitter, and a controller. The transmissionbuffer is configured to store a frame to be transmitted according to afirst protocol. The transmitter is coupled to the transmission buffer.The controller is coupled to the transmission buffer and the transmitterand is configured to determine whether the frame to be transmittedaccording to the first protocol is susceptible to being incorrectlyinterpreted by a receiver as being transmitted according to a secondprotocol. When the frame is determined to be susceptible to an incorrectinterpretation, an adjustment is made to an internal value of the frameand the adjustment is effective to prevent an incorrect interpretationof the frame. The controller is further configured to effecttransmission of the frame from the transmission buffer via thetransmitter.

Referring to FIG. 1, a tire pressure monitoring system 100 is shownassembled within a vehicle 102. The system 100 includes a receiver 106that receives communications from tire pressure monitoring devices 104(“monitors”) assembled within each of the vehicle's tires 108. Thereceiver 106 may be any communication device configured to receive anytype of transmitted communication but tuned to only recognize some ofthese communications. In one example, these communications are radiofrequency (RF) communications, but other types of communications arealso possible.

Although the device 104 is described as a tire pressure monitoringdevice herein, it will be appreciated that this device can gather andtransmit other types of information related to the tire in addition toor in place of tire pressure information. For example, the informationcan include temperature information or information related to the wearof the treads of the tire. Appropriate sensors or sensing devices may beused to obtain this information. Other examples of information may alsobe gathered by the tire pressure monitoring device 104.

Each of the tire pressure monitoring devices 104 are assembled withinthe tires 108 of the vehicle 102 and, as mentioned, communicateinformation indicative of conditions within the tires 108 to thereceiver 106. These conditions include temperature, pressure, and/or anyother desired information that aids in the evaluation of tireconditions. Other examples of conditions may also be sensed.

The system 100 includes the tire pressure monitoring devices 104 that inthis example includes a memory device 126. The memory device 126 isutilized for the storage of a control program 128. The control program128, once compiled and executed, transmits sensed information (e.g.,tire pressure information) according to one or more protocols (orformats) that govern operation and communication between the tirepressure monitoring device 104 and the receiver 106. Examples ofcommunication protocols that may be used include protocols that specifythe frequency and timing of transmissions from the tire pressuremonitoring device 104 to the receiver 106 or the format of transmission(such as what constitutes a “1” or a “0,” modulation type, errordetection and/or correction content, synchronization pattern, and soforth to not but a few examples in these regards). Tire pressuremonitoring information may be transmitted according to the protocolssequentially (e.g., using the same antenna) or at the same time (e.g.,using different antennas). In some aspects, no separate manufacturers'codes are used in making the transmissions. Once the control program iscompiled, the protocols that have been selected cannot be changedwithout changing (e.g., editing, compiling and installing anew) thecontrol program 128. In one aspect, the control program 128 is compiledand stored in the memory 126 during manufacturing.

In one aspect, the control program 128 may be executed continuouslywhenever the vehicle is moving. The control program 128 may also beexecuted when the vehicle is not moving, but only when the sensor isactivated externally (i.e., via LF or grounding of a pin on the ASICduring manufacturing). At other times, it may not be executed. However,learning the identities of the devices 104 (a “learning” process) and/ordetermining where each device is located (a “localization” process,e.g., front left, front right, and so forth) may be accomplished byusing an activation device 120. The activation device 120 emits awireless signal 122 (e.g., an LF signal) that is received by acorresponding one of the tire pressure monitoring devices 104. Receiptof the wireless signal 122 causes the device 104 to transmit identityinformation and also indicate to the receiver 106 that the device 104has received an LF signal and that the localization process can occur.When the vehicle is moving, LF transmitters (e.g., antennas) maytransmit LF signals (in place of the device 120). When moving, the RFsignals are periodically being transmitted and when the device 104 findsan LF signal, it so indicates to the receiver 106 (e.g., by flipping abit in the RF transmission). Once this indication is received,localization can be completed (e.g., this process may occur for apredetermined amount of time to ensure that the device 104 is correctlylocalized). Once localization is complete, tire pressure information canbe associated with a known tire. It will be appreciated that in otherexamples, the control program may itself be activated by the LF signals.

The activation device 120 includes a series of selectable buttons 124(or other types of actuators) that are actuated by a user to indicatethat they wish to activate the tire pressure monitoring device. Althoughthe example device 120 is shown with buttons, other display andselection configurations, such as touch screens, switches or some otherselection interface may be used as will be appreciated by those skilledin the art. Accordingly, installation of the multi applications tirepressure monitoring devices 104 optionally includes the initial step ofphysically activating the tire pressure monitoring devices 104 withineach of the corresponding tires 108 or activate a localization processthat allows tire pressure data to be associated with particular tires.

If an activation device is used, the activation device 120 is placedproximate to each of the tire pressure monitoring devices 104 to send asignal 122. In one example, the signal 122 is a low frequencytransmission received by the proximate tire pressure monitoring device104.

The devices 104 operate with the receiver 106 in the vehicle and thereceiver 106 typically has a display (or some sort of user interface)that is configured to alert the driver when the tire pressure fallsbelow a predetermined threshold value. As mentioned, once physicallyinstalled in the tire, the devices 104 are first “learned” by thecontrol unit. During this process, the receiver 106 determines theparticular identifiers and during or after learning, a localizationprocess may be executed in which each of the devices 104 is associatedwith a particular tire.

During normal operation (after the sensors are learned and localized andthe vehicle is moving), the device 104 senses the tire pressure andsends a radio frequency (RF) signal to the receiver 106 indicating thetire pressure. The receiver 106 can then determine if a pressure problemexists. If a problem exists, the user can be alerted so that appropriateaction can be taken. As mentioned, this is all accomplished by use of acontrol program that is compiled, translated, and/or assembled before itis executed. In one aspect, once compiled the structure of the controlprogram (e.g., the protocols selected) can not be changed. Also, nothingexternal to the device can be input into this control program to changethe structure of the control program once the control program (and theprotocols specified in the control program) is compiled. It will beappreciated that although many of the examples described herein refer toa control program being executed to transmit RF frames with tirepressure information, that other approaches can also be used. Forinstance, systems that utilize manufacturers' codes can also have theirmonitors localized according to the approaches described herein.

As mentioned, the devices 104 transmit tire pressure information. Thesignals that are transmitted include bursts that themselves includeplurality of frames and each of the frames includes the tire pressuremonitoring information. A plurality of pause spaces may be disposedbetween at least some of the frames in the burst. Characteristics of theframes in the burst or of the burst itself may be selected based uponcriteria such as government standards, industry requirements,periodicity requirements, or power requirements. Other examples ofcriteria are possible.

The characteristics of the signal may include the total number of framesin the burst, the relative positioning of the frames within the burst,the number of frames in the burst from each of plurality ofmanufacturers, and the relative positioning of the frames within theburst wherein at least some of the frames are from differentmanufacturers. Other examples of characteristics are possible.

The devices 104 are configured to make a determination is made as towhether a frame to be transmitted according to a first protocol issusceptible to being incorrectly interpreted by a receiver as beingtransmitted according to a second protocol. When the frame is determinedto be susceptible to an incorrect interpretation, the device 104 adjustsan internal value of the frame, and the adjustment is effective toprevent an incorrect interpretation of the frame being transmitted fromthe device 104 to a receiver in a vehicle. The adjusted frame can thenbe transmitted from the device 104.

In some aspects, the adjusting flips at least one bit in the frame. Inother aspects, the device 104 calculates a checksum in the frameaccording to the checksum determination made by the second protocol.Still further, the checksum may be compared to a field in the frame thatwould be the checksum field according to the second protocol. When thechecksum equals the value of the field, a possible misinterpretation mayoccur. When the possible misinterpretation may occur, at least one bitis flipped in the frame by the device 104.

The devices 104 can also receive indications as to whether the vehicleis moving. For example, a signal can be sent from the control unit ofthe vehicle with this information.

Referring now to FIG. 2, one example of an approach for transmittingsensed tire pressure information is described. At step 202, the tirepressure information is sensed. This can be accomplished by any tirepressure sensing mechanism as known to those skilled in the art.

At step 204, the sensed tire pressure information is stored in atransmission buffer. The transmission buffer may be part of a memory.

At step 206, a control program is executed to transmit the tire pressureinformation from the transmission buffer to an external receiver deviceaccording to each of a plurality of communications formats incorporatedinto the control program and not according to a manufacturers' code. Thecontrol program may be stored in the same memory as the transmissionbuffer or may be stored in a separate memory unit.

The control program may be compiled and/or assembled prior to itsexecution. The transmission of information according to each of theprotocols may be in predetermined block having a pre-defined format.Thus, separate blocks are used to transmit tire pressure information fordifferent protocols. Each of the blocks may be transmitted sequentiallyin a burst. A null space may be used to separate each of the blocks inthe burst.

The control program may also determine as to whether a frame to betransmitted according to a first protocol is susceptible to beingincorrectly interpreted by a receiver in a vehicle as being transmittedaccording to a second protocol. When the frame is determined to besusceptible to an incorrect interpretation, an internal value of theframe is adjusted, and the adjustment is effective to prevent anincorrect interpretation of the frame being transmitted from thetransmission buffer of the tire pressure monitor to the receiver.

As mentioned, the transmission buffer is configured to store tirepressure monitoring data and the transmitter is configured to transmit asignal including the tire pressure monitoring data. The signal includesa burst that includes plurality of frames and each of the framesincludes the tire pressure monitoring information. A plurality of pausespaces in some examples are disposed between at least some of the framesin the burst. Characteristics of the frames in the burst may be selectedbased upon criteria such as government standards, industry requirements,periodicity requirements, power requirements, or system requirements.Other examples of criteria are possible.

The characteristics of the signal (e.g., that are adjusted to meetgovernment standards, industry requirements, periodicity requirements,and/or power requirements) may include the total number of frames in theburst, the relative positioning of the frames within the burst, thenumber of frames in the burst from each of plurality of manufacturers,and the relative positioning of the frames within the burst wherein atleast some of the frames are from different manufacturers. Otherexamples are possible.

At step 208, the external receiver device may be configured to operateaccording to a selected one of the plurality of communication protocols.At the external receiver device (that is configured to operate accordingto a selected one of the plurality of communication protocols) receivesthe tire pressure information transmitted. At step 210, the receiverrecognizes the tire pressure information transmitted according to theselected one of the plurality of communication protocols and ignores thetire pressure information transmitted according to others of theplurality of communication protocols. Since the frame has been adjusted,misinterpretation problems are prevented from occurring.

Referring now to FIG. 3, an apparatus 300 for sensing tire pressureinformation is described. The apparatus 300 includes a sensing device302, a transmission buffer 304, a memory 306, a transmitter 308, and aprocessor (or controller) 310. One or more antennas 309 transmit RFsignals with the tire pressure information (e.g., in blocks, the blocksserially transmitted in bursts, each block having a predeterminedformat). One or more antennas 311 receive other communications (e.g., LFcommunications) that activate the apparatus 300 to transmit the RFsignals.

The sensor 302 that is configured to sense tire pressure information ofa tire. The sensor 302 is any mechanical sensing arrangement that sensesthe pressure of the tire as know to those skilled in the art.

The transmission buffer 304 is communicatively coupled to the sensingdevice and is configured to store the sensed tire pressure information.The transmission buffer 304 may be part of the memory 306 or separatefrom the memory 306 and is configured to store tire pressure monitoringdata. The transmission buffer is configured to store a frame to betransmitted according to a first protocol. The memory 306 may be anytype of memory storage device.

The transmitter 308 is coupled to the transmission buffer 304 and isconfigured to transmit signals. The transmitter 308 may have one or moreantennas 309 to transmit the signals. As mentioned, one or more antennas311 receive other communications (e.g., LF communications) that activatethe apparatus 300 to transmit the RF signals. These antennas may becoupled to the processor 310, which determines whether the signals meetcriteria that are required to activate the apparatus 300 and therebybegin transmitting the tire pressure information. The signal includes aburst that includes plurality of frames and each of the frames includesthe tire pressure monitoring information. A plurality of pause spaces isdisposed between at least some of the frames in the burst.Characteristics of the frames in the burst may be selected based uponone or more of: government standards, industry requirements, periodicityrequirements, or power requirements. Other examples are possible.

The characteristics of the signal relate to at least one characteristicsuch as the total number of frames in the burst, the relativepositioning of the frames within the burst, the number of frames in theburst from each of plurality of manufacturers, and the relativepositioning of the frames within the burst wherein at least some of theframes are from different manufacturers. Other examples are possible.

The processor 310 is communicatively coupled to the sensor 302, thetransmitter 308, the transmission buffer 304, and the memory 306. Theprocessor 310 is configured to execute a control program stored in amemory and execution of the control program is effective to transmit thetire pressure information from the transmission buffer 304 to anexternal receiver via the transmitter 308 according to each of aplurality of communications formats incorporated into the controlprogram and not according to a manufacturers' code.

The processor 310 is also configured to determine whether the frame tobe transmitted according to the first protocol is susceptible to beingincorrectly interpreted by a receiver as being transmitted according toa second protocol. When the frame is determined to be susceptible to anincorrect interpretation, an adjustment is made to an internal value ofthe frame and the adjustment is effective to prevent an incorrectinterpretation of the frame. The processor 310 is further configured toeffect transmission of the frame from the transmission buffer via thetransmitter.

In other aspects, a receiver 320 is configured to receive the tirepressure information transmitted according to each of the plurality ofcommunication protocols that is transmitted by the transmitter 308 atantenna 324 and communicate the information to processor 322 where theinformation can be processed. The receiver 320 is further configured torecognize the tire pressure information transmitted according to aselected one of the plurality of communication protocols and ignore thetire pressure information transmitted according to non-selected ones ofthe plurality of communication protocols.

Referring now to FIG. 4, one example of RF transmissions is described.In this example, a first burst 402 includes blocks (or frames) 404, 406,and 408. A second burst 420 includes frames 422, 424, and 426. Nullframes 410 are inserted between the frames, 406, 408, 410, 422, 424, and426.

Each of the blocks or frames 404, 406, 408, 422, 424, and 426 includestire pressure information. This information may be in the same ordifferent formats. In one example, all frames 404, 406, 408, 422, 424,and 426 include the information according to the protocol of a firstmanufacturer. In another example, frame 404 is in the protocol of afirst manufacturer, frame 406 is according to the protocol of a secondmanufacturer, frame 408 is in the protocol of the first manufacturer,frame 422 is in the protocol of a third manufacturer, frame 424 isaccording to the protocol of a fourth manufacturer, and frame 426 isaccording to the protocol of a fifth manufacturer. In still anotherexample, the frames are in the format of completely differentmanufacturers. In other aspects, a manufacturer may have differentformats. For instance, a first manufacturer may have a first format anda second format.

In one aspect, once the burst is sent, it is repeatedly transmitted. Therepetition is immediate and each new burst includes newly updatedinformation transmitted in each frame of the burst. In another example,once the first burst 402 is sent and then a predetermined time later(e.g., 17 seconds) the second burst is sent. Then, the pattern isrepeated.

In one aspect, the burst pattern cannot be changed by the user withoutthe control program being entirely re-programmed. That is, a programmingtool cannot be used to change the control program to transmit frames foradditional/different manufacturers and cannot be used to select framesto transmit.

Referring now to FIG. 5, one example of an approach to avoidmisinterpretation of frames in a tire pressure monitoring system isdescribed. At step 502, a determination is made by a tire pressuremonitor as to whether a frame to be transmitted according to a firstprotocol is susceptible to being incorrectly interpreted by a receiveras being transmitted according to a second protocol. This determinationmay be made if, for example, frames of two manufacturers are similarenough that a receiver expecting a frame from a second manufacturer mayconfuse a frame of first manufacturer as being from the secondmanufacturer. In this regard, information may be stored in memoryindicating frames of known types that can be misinterpreted along withactions to take when this situation occurs. In one approach, possiblemisinterpretation concerns are determined on a frame-by-frame basisafter each frame is loaded into the transmission buffer.

At step 504, when the frame is determined to be susceptible to anincorrect interpretation, an internal value of the frame is adjusted,and the adjustment is effective to prevent an incorrect interpretationof the frame being transmitted from the tire pressure monitor to areceiver in a vehicle. In some aspects, the adjusting flips at least bitin the frame. The adjusted frame can then be transmitted. In oneparticular example, a checksum is calculated in the frame according tothe checksum determination approach used by the second protocol. Stillfurther, the checksum is compared to a field in the frame that would bethe checksum field according to the second protocol. When the checksumequals the value present in the field, a misinterpretation problemexists. When the misinterpretation problem exists, at least one bit isflipped in the frame and the frame is transmitted. Flipping the bitensures that when a receiver expecting a frame of the second protocolreceives the frame (that has been actually transmitted according to thefirst protocol), the checksum will indicate an invalid frame accordingto the second protocol and the frame will be ignored by the receiver.

Referring now to FIG. 6, one example of an approach to avoidmisinterpretation of frames in a tire pressure monitoring system isdescribed. A first frame (frame 1) 602 is to be transmitted according toa first protocol (protocol 1). However, as shown in FIG. 6, the firstprotocol is similar to a second protocol that defines a second frame(frame 2) 604. For instance, it can be seen that the first field F1 ofthe frame 602 corresponds to the first field F1 of the frame 604; thatthe second field F2 of the frame 602 corresponds to the second field F2of the frame 604; and that the third field F3 of the frame 602corresponds to the third field F3 of the frame 604. A receiver expectinga frame transmitted corresponding to the second protocol (i.e., frame604) but actually receiving the frame transmitted according to the firstprotocol (i.e., frame 602) may calculate a checksum on the receivedframe 602 and if this checksum equals field F4 in frame 602, then thereceiver will accept the frame 602 as being of the second protocol. Inother words, the receiver expecting to receive a frame according toprotocol 2 may misinterpret a frame transmitted according to protocol 1,thereby creating problems at the receiver.

At step 604 the monitor calculates the checksum of frame 602 as it wouldbe calculated for a frame being transmitted according to protocol 1. Ifthe calculation produces a value that equals the value in field F4 offrame 602, a potential misinterpretation problem exists and anadjustment is made in frame 602 so that when this frame is received at areceiver expecting a frame of protocol 2, a misinterpretation isavoided. This can be accomplished, for example, by flipping a bit in theframe 602. By flipping a bit, the checksum computed by the receiver(expecting a frame of protocol 2) will not match the field F4 in frame602 and the receiver will ignore the frame (since the calculatedchecksum indicates a corrupted frame). If the original calculation showsthat the checksum is different, no bit flipping (or other adjustment) isneeded and the receiver (expecting a frame of the second protocol) willsimply ignore the frame.

It should be understood that any of the devices described herein (e.g.,the programming or activation devices, the tire pressure monitoringdevices, the receivers, the transmitters, the sensors, the presentationdevices, or the external devices) may use a computing device toimplement various functionality and operation of these devices. In termsof hardware architecture, such a computing device can include but is notlimited to a processor, a memory, and one or more input and/or output(I/O) device interface(s) that are communicatively coupled via a localinterface. The local interface can include, for example but not limitedto, one or more buses and/or other wired or wireless connections. Theprocessor may be a hardware device for executing software, particularlysoftware stored in memory. The processor can be a custom made orcommercially available processor, a central processing unit (CPU), anauxiliary processor among several processors associated with thecomputing device, a semiconductor based microprocessor (in the form of amicrochip or chip set) or generally any device for executing softwareinstructions.

The memory devices described herein can include any one or combinationof volatile memory elements (e.g., random access memory (RAM), such asdynamic RAM (DRAM), static RAM (SRAM), synchronous dynamic RAM (SDRAM),video RAM (VRAM), and so forth)) and/or nonvolatile memory elements(e.g., read only memory (ROM), hard drive, tape, CD-ROM, and so forth).Moreover, the memory may incorporate electronic, magnetic, optical,and/or other types of storage media. The memory can also have adistributed architecture, where various components are situated remotelyfrom one another, but can be accessed by the processor.

The software in any of the memory devices described herein may includeone or more separate programs, each of which includes an ordered listingof executable instructions for implementing the functions describedherein. When constructed as a source program, the program is translatedvia a compiler, assembler, interpreter, or the like, which may or maynot be included within the memory.

It will be appreciated that any of the approaches described herein canbe implemented at least in part as computer instructions stored on acomputer media (e.g., a computer memory as described above) and theseinstructions can be executed on a processing device such as amicroprocessor. However, these approaches can be implemented as anycombination of electronic hardware and/or software.

Those skilled in the art will recognize that a wide variety ofmodifications, alterations, and combinations can be made with respect tothe above described embodiments without departing from the spirit andscope of the invention, and that such modifications, alterations, andcombinations are to be viewed as being within the scope of theinvention.

What is claimed is:
 1. A method of avoiding protocol misinterpretationin a tire pressure monitoring system, the method comprising: determiningwhether a frame to be transmitted according to a first protocol issusceptible to being incorrectly interpreted by a receiver in a vehicleas being transmitted according to a second protocol; when the frame isdetermined to be susceptible to an incorrect interpretation, adjustingan internal value of the frame, the adjusting being effective to preventan incorrect interpretation of the frame being transmitted from the tirepressure monitor to the receiver.
 2. The method of claim 1 furthercomprising transmitting the adjusted frame.
 3. The method of claim 1wherein the adjusting flips at least one bit in the frame.
 4. The methodof claim 1 wherein the determining comprises calculating a checksum inthe frame according to a checksum determination approach used by thesecond protocol.
 5. The method of claim 4 wherein the checksum iscompared to a field in the frame that would be the checksum fieldaccording to the second protocol.
 6. The method of claim 5 furthercomprising when the checksum equals the value of the field, a possiblemisinterpretation exists.
 7. The method of claim 6 further comprising,when the possible misinterpretation exists, at least one bit is flippedin the frame.
 8. An apparatus for avoiding protocol misinterpretation ina tire pressure monitoring system, the apparatus comprising: atransmission buffer configured to store a frame to be transmittedaccording to a first protocol; a transmitter coupled to the transmissionbuffer; a controller coupled to the transmission buffer and thetransmitter, the controller configured to determine whether the frame tobe transmitted according to the first protocol is susceptible to beingincorrectly interpreted by a receiver as being transmitted according toa second protocol, and when the frame is determined to be susceptible toan incorrect interpretation, to adjust an internal value of the frame,the adjustment being effective to prevent an incorrect interpretation,the controller further configured to effect transmission of the framefrom the transmission buffer via the transmitter.
 9. The apparatus ofclaim 8 wherein the controller is configured to adjust by flipping atleast one bit in the frame.
 10. The apparatus of claim 8 wherein thecontroller is configured to calculate a checksum in the frame accordingto a checksum determination approach used by the second protocol. 11.The apparatus of claim 10 wherein the controller is configured tocompare the checksum to a field in the frame that would be the checksumfield according to the second protocol.
 12. The apparatus of claim 11wherein the controller is configure to when the checksum equals thevalue of the field, determine that a possible misinterpretation exists.13. The apparatus of claim 12 wherein the controller is configured to,when the possible misinterpretation exists, flip at least one bit in theframe.
 14. A computer usable medium having a computer readable programcode embodied therein, said computer readable program code adapted to beexecuted to implement a method of avoiding protocol misinterpretation ina tire pressure monitoring system, the method comprising: determiningwhether a frame to be transmitted according to a first protocol issusceptible to being incorrectly interpreted by a receiver as beingtransmitted according to a second protocol; when the frame is determinedto be susceptible to an incorrect interpretation, adjusting an internalvalue of the frame, the adjusting being effective to prevent anincorrect interpretation of the frame being transmitted from the tirepressure monitor to a receiver in a vehicle.
 15. The computer usablemedium of claim 14 wherein the method further comprises transmitting theadjusted frame.
 16. The computer usable medium of claim 14 wherein themethod further comprises adjusting flips at least one bit in the frame.17. The computer usable medium of claim 14 wherein the determining ofthe method further comprises calculating a checksum in the frameaccording to a checksum determination approach used by the secondprotocol.
 18. The computer usable medium of claim 17 wherein thechecksum is compared to a field in the frame that would be the checksumfield according to the second protocol.
 19. The computer usable mediumof claim 18 wherein the method further comprises when the checksumequals the value of the field, a possible misinterpretation exists. 20.The computer usable medium of claim 19 wherein the method furthercomprises, when the possible misinterpretation exists, flipping at leastone bit in the frame.
 21. A computer usable medium having a computerreadable program code embodied therein, said computer readable programcode adapted to configure a controller of an apparatus for avoidingprotocol misinterpretation in a tire pressure monitoring system, suchthat the following means are formed on the controller: means fordetermining whether a frame to be transmitted according to a firstprotocol is susceptible to being incorrectly interpreted by a receiveras being transmitted according to a second protocol; means for, when theframe is determined to be susceptible to an incorrect interpretation,adjusting an internal value of the frame, the adjusting being effectiveto prevent an incorrect interpretation of the frame being transmittedfrom the tire pressure monitor to a receiver in a vehicle.